In Japan, nutritional therapy as both a primary and as a secondary treatment is widely used for Crohn's disease (CD). The rationale for its use is based on a variety of reasons. The first is its ability to induce remission and to ameliorate the activity of intestinal lesions in the short term by enteral (EN) or by parenteral nutritional therapy in which overexpressions of chemokine receptors in an active stage are decreased significantly in the remission stage. Second is its ability to maintain remission over the long term through home-based enteral nutrition in which tube feeding during the nighttime is encouraged. Third is its ability to reduce the steroid dosage over the period of a long-term treatment course. However, several disadvantages of this therapy such as unpalatability and sluggish effect have been pointed out. Several studies have attempted to resolve this issue and determine the best components of EN, especially in fat composition. Some data have been suggestive of too much long-chained fatty acid having a hazardous effect on EN's clinical efficacy because it works as a precursor of inflammatory prostaglandins. Our recent data show that medium-chained triglyceride did not have such a hazardous effect on clinical efficacy. Several studies suggested that the patient factors that were resistant to inducing remission in the short term were a long period of suffering CD, a high activity (on Crohn's Disease Activity Index, CDAI), hemorrhagic colitis, and colitis with marked cobblestoning. Japanese guidelines for the treatment of CD recommended nutritional therapy as a first-line therapy and as a maintenance therapy after inducing remission. This treatment policy has led to Japanese CD patients having lower mortality rates than that of patients who do not receive EN. If this therapy could be combined with other drug therapies, including strong immunosuppressants, treatment strategies would be improved over those we have at present.